<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <!--外部引入js文件-->
    <script src="../../js/demo01.js"></script>
    <!--内部就是书写方式-->
    <script>
        alert("Hello 宋虹桥")
    </script>
</head>
<body>

</body>
</html>